Means of transmitting intelligence.



R. A. FESSENDEN.

MEANS OF TRANSMITTING vINTELLIGEIJCE. APPLICATION FILED 05c. 23, 1907.

Patented. Feb. 8, 1916;

2 SHEETSSHEET I.

INVENTOR.

R. A. FESSENDEN. MEANS OF TRANSMITTING INTELLIGENCE.

APPLICATION FILED DEC. 23, 1907- I 1,17,969. Patented Feb. 8, 1916.

2 SHEETSSHEET 2.

t i l i flf T u AIM 3/ IN VEN TOR.

REGINALD A. FESSENDEN, OF BRANT ROCK, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 SAMUEL M. KINTNER, 0F PITTSBURGH, PENNSYLVANIA, AND I'IALSEY M. BARRETT, OF BLOOMFIELD, NEW JERSEY, RECEIVERS.

Specification of Letters Patent.

Patented Feb. 8, 1916.

Application filed December 23, 1907. Serial No. 407,750.

provements the following is a specification.

My invention relates to electric signaling and more particularly to wireless signaling by electromagnetic waves.

In the accompanying drawings forming a 1 part of this specification Figure 1 shows in diagram an arrangement for carrying out the object of this invention. Fig. 2 shows an alternative arrangement.

The invention herein disclosed. has for its object the securing of absolute secrecy in the transmission of wireless messages and transmission without producing any disturbances on nearby stations, and the attainment of high speed, and the transmission and receipt of messages simultaneously.

In the practiceof my invention, instead of sending dots and dashes I send dots only,

which are to be interpreted as dots and dashes according to the time of their receipt at the receiving station, the determination of whether a signal is a dot or dash being thus impossible without a knowledge of the exact time interval employed. By this means in addition to absolute secrecy greater speed is obtained.

I alsoprefer to use my method of sending by generating oscillations continuously and producing a signal by varying the frequency. I also prefer, at the receiving end to use my heterodyne method of receiving.

, The method of operation can, however, 0b-

viously be used with other'well known methods of transmitting and receiving signals and I do not therefore limit myself to the particular arrangement herein described.

In Fig. 1, 11 is an antenna grounded, at 12;'and 13, 14 are primaries of transformers connected to a source for continuously generating waves, for example the spark gap 15, a continuous current dynamo 16 and variable resistance 17. and 19 an inductance used for tuning the high frequency oscillating circuit. '20 and 18 is a condenser 21 are metallic disks with insulating segments so arranged that one connects with its brush in advance of the other but the two overlap in position, their shaft 20 being driven by the electric motor 22, whose field current is regulated by the battery 23, and adjustable resistance 24. This motor is maintained at constant speed by any suitable means such as the tuning fork 25, by the method described in U. S. Patent- 727,326. 26 andv27 are brushes mounted on the arm 28. This arm is attached to the gear disk 29, in such a Way that on depressing the keys 30 and 31, and so closing the circuits containing the local battery 33 and the clutch mechanism 34 the disk 29 will be revolved by the threaded shaft 34*, to the left or right according .to which of the friction disks 34 is' in engagement with disk 34, and thus the position of the brushes is advanced or brought back. 35, 36, 37 are taps from the inductance 19. 38,39, 43 are switches electrically actuated by the keys 40 and 41 and the local battery 42.- 44 is a coil attached to the diaphragm of the transmitter 45 and 46 is a fixed coil operv ated by the secondary coil 47 of the trans: former whose primary is the coil 14. 48' is the secondary coil of a transformer whose primary is 13. 47, 48, 49 are adjustable resistances. In operation the keys 40 and 41 being in the released position, the switch 50 being open and the circuit closer 43 being pulled over to the left by the spring 51, and the switches 38, 39 closed the commutator disks 20 and 21, in revolving cause elec-j tromagnetic waves of three different frequencies to be radiated: 1: The normal frequency which we will call 100,000. 2: A

; higher frequency when the brush 27' is on when the brush 26 also comes on to the me-- 'tallic portion of the disk 20, thereby short circuiting a still larger amount of the inductance 19. This we may take as 100,200. Three frequencies of 100,000, 100,100, and 100,200 are therefore radiated continuously in sequence with each other. On dc pressing the key 41 the switch 39 is opened and the sequence then becomes 100,000, 100,000, and 100,200. The depression of this key we may take as the sending of a dot. On depressing the key 40 the switch 38 is opened and the sequence becomes 100,000, 100,100 and 100,000. The depression of this key we may take as the sending of a dash.

In this way the signals are transmitted.

Assume now that messages are being transmitted by a station using. this arrangement and being received at a station using a similar arrangement. At the receiving station the keys 40 and 41 are still in a released position but the switch 50 is closed and the circuit closer 43 is thrown over as shown to the right. Obviously oscillations will flow continuously through the coil 46, the oscillations being uninterrupted. but the frequency varying in the sequence 100,000,

100,100, and 100,200. The received signals will flow from the antenna 11 through the coil 44 to ground, and no indication will be produced. if the disks 20 and 21 rotate at the same frequency, and have the same angular position as the disks at the sending station. If, however, the disks are not in synchronism, musical chords will be produced and the operator at the receiving station depresses one of the keys 30 or 31 and so ro tates the brushes 26, 27 until silence is obtained. If after a short period the chords begin to be heard again the operator moves the adjusting nut 52 on the tuning fork 25 in such a way to obtain synchronism. In actual operation it is found extremely difficult even by.the use of compressed air condensers, constant temperature boxes, etc., to

maintain the high frequency circuits at the sending and receiving stations absolutely constant, but this is not necessary, asthe' operator, instead of adjusting the brushes to zero sound, adjusts them until a single note is heard instead of a chord, since when this is the case the disks are in synchronism and phase. Also it is impossible to maintain this synchronism absolutely, and after a longer or shorter period of time the chords begin to be audible again, and gradually swell in intensity, but the operator controls thls by per secondwill be formed between the secand members of'the two series, z'. e; a musical note having that frequency will be heard byrth'e'ear of the operator, the receiver 45 being attached to the operators head. A note of this frequency is recognized by the operator as representing a dot. On the key corresponding to 40 being depressed at the sending station, the sequence sent out will be 100,000, 100,100, and 100,000 andbeats will now be produced between the three members of the series having a frequency of 200 per second, and the musical note of this frequency will be understood by the operator to represent a dash. In operation therefore, when the high frequency circuits are identical in frequency spaces will be represented by silence, dots by a musical note of 100 per second and dashes by a musical note of 200 per second. Should the frequencies diifer by say 150 per second, spaces will be represented by a musical note of 150 per second, dots by amusical note of 250 per second and dashes by a musicalnote of 350 per second.

The following points are obvious: .1: That no other station can interpret the message transmitted without knowing the number of commutator segments and their exact speed- 7 of revolution, and as there is no means whereby anoutside station can determine this, absolute secrecy is obtained. 2: Also that since the oscillations are generated continuously and of constant strength, (the restances 47, 48, 49 being used to regulate this where necessary) and merely the tune is slightly changed therefore no disturbance will be produced on other stations. unless they are' using exactly the same range of tune. This is for the reason that even if the electrical oscillations are received by the mother station, no sound will be produced on accountof the oscillations being continuous and uninterrupted. 3: Also that greater speed can be obtained, since there is no space necessary between the dot and dash elements in sending a letter; For instance the Morse letter D sent the present way occupies a time equal to 9 dots whereas by the method hereilnv described it occupies the time of three ots.

Fig. 2 shows the 1 apparatus adapted to sending and receiving simultaneously. Elements identical with Fig. 1 are numbered identically. Instead of the oscillatory circuit containing the discharge gap 15, condenser 18, and inductance 19, acting directly on the secondary. 48, it acts through the primaries 53, 54, 55, 56 on the circuit containing the secondaries 5 7, 58, 59, 60, the

variable capacity 61, the resistances.62,. 63,

the fixed coil 64 and the primary 65. The coil 44 instead of 'being attached to, the antenna is connected as shown to the middle point of the above mentioned circuit through the inductance 66 andvariable capacity 67.

With this arrangement it is possible for the operator to listen in at the same time that he is sending, since the coil 44 being in a I.- J

- a current controlling device in uniform mo- .tion at the receiving station, means to adjust the motion of the latter device independently of the former, but synchronously therewith, and means to cause impulses emitted from the sending station by means of the said controlling device to produce different effects at the receiving station according to the relative positions of the said two synchronous current controlling devices at the time of sending. I

2. Electric signaling apparatus comprising a enerator'and a-receiver, two synchrono'us requency controlling devices respectively at the sending and receiving stations, means causing impulses due to said frequency controllin devices to normally annul each others e ects, and means to produce an indication by altering the relative phases of the synchronous devices, the indication depending upon the relation of phases, substantially as described.

3. Electric signaling apparatus comprising means for continuously sending a series of cycles of impulses, means to maintain independently at other; stations a series of similar cycles, and means to, produce a signal by altering the character of the individual impulses in the transmitted cycle.

4. Electrical signaling apparatus comprising means to locally maintain a stream of cycles of' impulses, means to annul their effects by independent but synchronous cycles of impulses sent from another station, and means to sensibly indicate changes in the character of the individual impulses in the cycles sent.

' 5. Electrical signaling apparatus comprising sending and receiving circuits having independent means to maintain synchronous streams of orderly cycles of impulses in each circuit, means to normally annul their effects on each other, means to variously alter the character of the impulses in a cycle in one circuit, and means in the other by which said alterations produce sounds of predetermined character, for signaling.

6. Electric signaling apparatus comprising means to. automatically send separate cycles of impulses divided'into groups of predetermined character, a receiving indicator and means at the receiving station to normally suppress the effects of said cyclesof impulses sent, means to vary the character of several of the groups in the cycles sent,

and means to produce at the receiving station different indications according to the group in the cycle which is changed.

7. Electric signaling apparatus comprising means to senda continuous series of groups of impulses of predetermined char. acter, devices to alter the frequency of one .of said groups to represent a dot, and another of said groups to represent a dash,

receivingimechanism adapted to respond in a different Way for the dot groups andthe dash groups, substantially as described.

8. Electric signaling apparatus comprising means to send a continuous stream of electric impulses, means to separate said stream into predetermined cycles of wave alterv said character, and receiving mechanism adapted to respond with different indications accordingto the one of the trains in the cycle \vliich'is altered in character.

9. Electric signaling apparatus comprising devices sending a continuous series of recurring regular cycles of Wave trains, means to alter the frequency of particular cycles, a receiver, controlling devices at the receiving station adapted to cause the receiver to respond to said waves sent, with a different indication for each cycle frequency.

10. Electric signaling apparatus comprising means to continuously send a stream of electromagnetic waves, devices'to separate said stream of Waves into cycles of groups of varying frequency, means to Vary the frequency in any one of the groups, and a receiving apparatus adapted to respond with different kinds of indications dependent which comprises sending continuously orderly cycles of groups of impulses, varying the frequency of particular groups in the cycle, and at the receiver producing a difierent kind of indication thereby, according to the group of impulses in the cycle which is altered in character.

13. In wireless telegraphy, the method Which comprises sending continuous series of cycles of impulses respectively differingin characteristics, varying groups in the cycles and at the receiving station actuating trains of different character, and means to an indicator by selecting the particular group in a cyclewhose frequency is varied.

14:. In wireless telegraphy, the method of signaling by changing the frequency of particular groups in a cycle of varying groups of the impulses without interrupting the continuity, and producing an indication dependent for its character upon the change in frequency.

15. The method of wireless signaling which comprises sending and receiving a continuous stream of impulses, periodically altering the characteristics of such impulses in orderly groups of Waves at the sending station, and at the receiving station actuating an indicator with different characters according to the order of succession of the groups whose characteristics change.

16. The method of electric signaling which consists in sending and receiving a continuous stream of impulses in series having nor mally uniform intensity and signaling by changing the frequency of impulses periodically with a varying order of succession of periods, substantially as described.

17. The method of electric signaling which consists in sending and receiving a continuous train of impulses divided into distinct ments of a signal at difl erent phases of the movement of the current controlling devices and thereby differentiating the elements of the signal.

In testimony whereof I have hereunder signed my name inthe presence of .the subscribed witnesses.

REGINALD A. FESSENDEN. Witnesses:

Jnssm E. BENT, J. W. L'EE. 

